Question

I have two queries which i would like to combine
There are 4 tables which are linked.
user, group, policy, source

1st query i get the users with the respective policy id.

1st Query:

Select users.ID as UserID,users.Username,   
policy.ID as PolicyID,policy.PolicyName 
from users join groups on group.ID = user.groupID_FK 
join policy on users.policyID_FK = policy.ID

2nd Query: Here i need to match the policyID_FK and apply the path. the source type should be 0, it is possible that there is no entry of datasource type o for that policyID_FK .

Select Path, policyID_FK from source
WHERE SourceType = 0 and policyID_FK  = 1

Here instead of giving policyID_FK = 1 i want to join this query with the above query.

Please help. I know i am not much clear but please ask if you don’t understand something.

Thanks

Answer 1

Select users.ID as UserID,users.Username, policy.ID as PolicyID,policy.PolicyName, source.Path
from users join groups on group.ID = user.groupID_FK 
   join policy on group.policyID_FK = policy.ID
   left join source
      on group.policyID_FK = source.policyID_FK
      and SourceType = 0 

Use left join when you know that right table might not have matching records. Append any filter you have beside join to left-join filter, because if you put it in where it will remove rows you want to retrieve.